(CNSNews.com) – Republican presidential candidate Mitt Romney weighed into the Fast and Furious scandal Friday, supporting the congressional investigation into the matter and heralding the demands that Attorney General Eric Holder resign.

Operation Fast and Furious was a Justice Department program that began in September 2009 in which law enforcement knowingly allowed about 2,000 U.S. guns to flow to Mexican drug cartels, with the intent of tracking the weapons and making arrests.

However, law enforcement lost track of most of the weapons. The program was halted in December 2010 after two weapons from the program were found at the murder scene of Border Patrol Agent Brian Terry.

Sen. Charles Grassley (R-Iowa) first raised questions about the matter, and the House Oversight and Government Reform Committee, chaired by Rep. Darrell Issa (R-Calif.), has led the investigation.

Romney spoke Friday in St. Louis at the Annual Meeting of the NRA, the nation’s leading pro-Second Amendment group.

“I applaud Congressman Issa and Sen. Grassley for their work in exposing the Fast and the Furious scandal,” Romney, a former Massachusetts governor, said to enthusiastic applause.

“And of course I applaud the NRA leadership for being among the first and most vocal in calling upon Attorney General Holder to resign or get fired,” Romney said, followed by nearly 30 seconds of applause from the audience.

Already more than 100 members of Congress have called on Holder to resign from office regarding his mishandling of the operation. Holder has contended that he was unaware that guns were allowed to “walk.”

While praising the NRA’s support for Holder to step down, Romney did not specify whether he believed Holder should resign.